Ru Dye Uptake under Pressurized CO[sub 2] Improvement of Photovoltaic Performances for Dye-Sensitized Solar Cells

Swift uptake of Ru dyes and improvement of photovoltaic performances for dye-sensitized solar cells (DSC) are reported. Ru dyes such as black dye [ ( -tricarboxy- -terpyridine) and N3 dye [ cis -di(thiocyanato)- -bis( -bipyridyl- -dicarboxylato) ruthenium (II)] are adsorbed on nano-porous layers under a pressurized atmosphere to bond Ru dyes on inner surfaces of in nano-porous layers effectively. The time needed for N3 dye adsorption under a pressurized condition is drastically shortened to from needed for a dipping process. The amount of N3 dye molecules increases from when N3 dye is adsorbed under a pressurized atmosphere. The pressurized process increases short circuit current, fill factor, and open circuit voltage which are associated with better coverage of surfaces with dye molecules. They decrease surface traps of porous layers. This retards back electron transfers from layers to iodine in electrolytes and facilitates electron diffusion in layer. Measurement of the electron lifetime and electron diffusion coefficient in the cells supports the mechanism.